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// SPDX-License-Identifier: GPL-2.0
/*
* BME680 - SPI Driver
*
* Copyright (C) 2018 Himanshu Jha <himanshujha199640@gmail.com>
*/
#include <linux/module.h>
#include <linux/of.h>
#include <linux/regmap.h>
#include <linux/spi/spi.h>
#include "bme680.h"
struct bme680_spi_bus_context {
struct spi_device *spi;
u8 current_page;
};
/*
* In SPI mode there are only 7 address bits, a "page" register determines
* which part of the 8-bit range is active. This function looks at the address
* and writes the page selection bit if needed
*/
static int bme680_regmap_spi_select_page(
struct bme680_spi_bus_context *ctx, u8 reg)
{
struct spi_device *spi = ctx->spi;
int ret;
u8 buf[2];
u8 page = (reg & 0x80) ? 0 : 1; /* Page "1" is low range */
if (page == ctx->current_page)
return 0;
/*
* Data sheet claims we're only allowed to change bit 4, so we must do
* a read-modify-write on each and every page select
*/
buf[0] = BME680_REG_STATUS;
ret = spi_write_then_read(spi, buf, 1, buf + 1, 1);
if (ret < 0) {
dev_err(&spi->dev, "failed to set page %u\n", page);
return ret;
}
buf[0] = BME680_REG_STATUS;
if (page)
buf[1] |= BME680_SPI_MEM_PAGE_BIT;
else
buf[1] &= ~BME680_SPI_MEM_PAGE_BIT;
ret = spi_write(spi, buf, 2);
if (ret < 0) {
dev_err(&spi->dev, "failed to set page %u\n", page);
return ret;
}
ctx->current_page = page;
return 0;
}
static int bme680_regmap_spi_write(void *context, const void *data,
size_t count)
{
struct bme680_spi_bus_context *ctx = context;
struct spi_device *spi = ctx->spi;
int ret;
u8 buf[2];
memcpy(buf, data, 2);
ret = bme680_regmap_spi_select_page(ctx, buf[0]);
if (ret)
return ret;
/*
* The SPI register address (= full register address without bit 7)
* and the write command (bit7 = RW = '0')
*/
buf[0] &= ~0x80;
return spi_write(spi, buf, 2);
}
static int bme680_regmap_spi_read(void *context, const void *reg,
size_t reg_size, void *val, size_t val_size)
{
struct bme680_spi_bus_context *ctx = context;
struct spi_device *spi = ctx->spi;
int ret;
u8 addr = *(const u8 *)reg;
ret = bme680_regmap_spi_select_page(ctx, addr);
if (ret)
return ret;
addr |= 0x80; /* bit7 = RW = '1' */
return spi_write_then_read(spi, &addr, 1, val, val_size);
}
static struct regmap_bus bme680_regmap_bus = {
.write = bme680_regmap_spi_write,
.read = bme680_regmap_spi_read,
.reg_format_endian_default = REGMAP_ENDIAN_BIG,
.val_format_endian_default = REGMAP_ENDIAN_BIG,
};
static int bme680_spi_probe(struct spi_device *spi)
{
const struct spi_device_id *id = spi_get_device_id(spi);
struct bme680_spi_bus_context *bus_context;
struct regmap *regmap;
int ret;
spi->bits_per_word = 8;
ret = spi_setup(spi);
if (ret < 0) {
dev_err(&spi->dev, "spi_setup failed!\n");
return ret;
}
bus_context = devm_kzalloc(&spi->dev, sizeof(*bus_context), GFP_KERNEL);
if (!bus_context)
return -ENOMEM;
bus_context->spi = spi;
bus_context->current_page = 0xff; /* Undefined on warm boot */
regmap = devm_regmap_init(&spi->dev, &bme680_regmap_bus,
bus_context, &bme680_regmap_config);
if (IS_ERR(regmap)) {
dev_err(&spi->dev, "Failed to register spi regmap %ld\n", PTR_ERR(regmap));
return PTR_ERR(regmap);
}
return bme680_core_probe(&spi->dev, regmap, id->name);
}
static const struct spi_device_id bme680_spi_id[] = {
{"bme680", 0},
{},
};
MODULE_DEVICE_TABLE(spi, bme680_spi_id);
static const struct of_device_id bme680_of_spi_match[] = {
{ .compatible = "bosch,bme680", },
{},
};
MODULE_DEVICE_TABLE(of, bme680_of_spi_match);
static struct spi_driver bme680_spi_driver = {
.driver = {
.name = "bme680_spi",
.of_match_table = bme680_of_spi_match,
},
.probe = bme680_spi_probe,
.id_table = bme680_spi_id,
};
module_spi_driver(bme680_spi_driver);
MODULE_AUTHOR("Himanshu Jha <himanshujha199640@gmail.com>");
MODULE_DESCRIPTION("Bosch BME680 SPI driver");
MODULE_LICENSE("GPL v2");
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